Preformed surfacing for pavements

ABSTRACT

A preformed surfacing for a pavement is in the form of a sheet of flexible material containing cavities open to its upper surface and interconnected by ducts beneath the surface so that when laid down on a prepared subsurface having a drainage slope, water falling on the surfacing can drain away through the cavities and ducts. The sheet can be fixed to the subsurface by anchors bonded into cavities in the sheet.

United States Patent 1191 1111 3332,02 Judge et al. 1 1 May 8, 1973 [54] PREFORMED SURFACING FOR [5 6] References Cited PAVEMENTS UNITED STATES PATENTS [75] Inventors: Raymond Frank Aspinale Judge, I

London; Frederick Royal Martin Bmmemmth; Russell George 2:023:30? 12 1935 Burton IQ ...,,::94 11 M011, calshalmn, O England 619,934 2 1299 Buchtel ....94 33 x 2,999,431 9 1961 Mitchell ..94 13 [73] Asslgnee' secritary. a 3,407,713 10/1968 Heckman 1.94 7 x f' er 3,040,637 6/1962 Bremshey ....94 11x -I Y Gmemment the Umted 2,057,738 10 1936 Pipes ..94 11 Kingdom of Great Britain and Northern Ireland Filed: Feb. 4, 1971 Appl. No.: 112,668

Primary ExaminerNile O. Byers, Jr. Attorney-Cameron, Kerkam & Sutton [57] ABSTRACT A preformed surfacing for a pavement is in the form Foreign Application Priority Data of a sheet of flexible material containing cavities open to its upper surface and interconnected by ducts b. 4 70 G Fe reat Bntaln 5358/70 beneath the surface so that when laid down on a prepared-subsurface having a drainage slope, water 5 ig 5i i g3 falling on the surfacing can drain away through the u cavities and ducts. The sheet can be fixed to the suble 0 Earl! 1 7, 921/33 surface by anchors bonded into cavities in the sheet.

13 Claims, 3 Drawing Figures a e 15 1% a e e H PMENTEW ;732'.020

SHEET 2 OF 2 PREFORMED SURF ACING FOR PAVEMENTS This invention relates to preformed surfacing for pavements and more specifically, though not exclusively, to a multi-purpose preformed surfacing for roads and airfield pavements.

Pavements constructed in accordance with traditional practise are subject to various disadvantages. For instance one of the most common causes of loss of adhesion of aircraft or motor vehicle tyres on a pavement is the formation of a layer of water between the tyre and the pavement during or as the result of rain. Even where a pavement is sloped to shed the water to drainage channels during heavy rain the time of runoff, particularly if it is against the wind, can be suffiwhich is both strong and economic on material. Any other regular pattern of cavities may be used, for examplc a rectangular pattern of square cavities.

An embodiment of the invention will now be described by way of example with reference to the following drawings of which:

cient for a layer of water to build up and be maintained over the surface. Accumulated water can lead to the phenomenon of aqua planing which occurs when a wheel, rolling at high speed over a wet surface, tends to ride on water unable to drain sufficiently quickly from the point of contact between the wheel and the surface. When this happens there is a large reduction in adhesion and directional stability between the wheel and the pavement.

All pavements wear and have to be closed in part or in whole periodically for maintenance. In traditional construction this can mean the complete closure for use of an aerodrome runway or road for some considerable period.

Both aerodrome pavements and roads are marked on the surface with various signs to direct the traffic. These surface marking wear and again inconvenience is caused by remarking.

The present invention is directed to providing a preformed surfacing for pavements which obviates the above disadvantages of traditional construction.

According to the present invention, a preformed surfacing for a pavement comprises a sheet of flexible material laid down on a prepared subsurface having a drainage slope, said sheet having a plurality of cavities therein which are open to the uppermost surface of the sheet and having ducts not open to the uppermost surface communicating between adjacent cavities, there being ducts from each cavity to at least three adjacent cavities so that in use liquid can drain away from the sheet down the direction of the drainage slope of the prepared subsurface. Preferably at least some of the cavities are through cavities from the uppermost surface to the lowermost surface and the interconnecting ducts are grooves or channels formed in the lowermost surface of the sheet.

In accordance with an important feature of the invention, the sheet is provided with a plurality of fixing heads or anchors at discrete intervals whereby it can be anchored to the subsurface, each fixing head preferably being located in one of the said drainage cavities in the sheet.

The material of which the sheet is formed is flexible so that the sheet can adequately conform to the underlying subsurface and, if required, can be laid down by uncoiling from rolls.

In a preferred arrangement of the present invention the cavities are of the same size and shape and are regularly spaced. Avantageously cavities having a circular or regular hexagonal section may be used enabling a close packed honeycomb type structure to be formed FIG. 1 is a plan view of part of a preformed surface for a pavement constructed in accordance with the invention.

FIG. 2 is a sectional elevation on the line lI-ll of FIG. 1.

FIG. 3 is a sectional elevation of a modification.

A preformed surface for a pavement is constructed as shown in the FIGS. 1 and 2 from a sheet 1 of material of uniform thickness having a flat upper surface 2 parallel to a flat lower surface 3. The sheet 1 contains a number of drainage cavities hereinafter referred to as perforations 4 each of which has a uniform regular hexagonal section. The axis of each of the perforations 4 is normal to both surfaces and they are all of the same size. All the perforations 4 are orientated in the same direction so that each flat side 7 of any particular perforation 4 is parallel to an adjacent flat side 7 of a neighbouring perforation 4, defining the boundaries of walls 5 separating the perforations 4. Thus each perforation 4 has six such walls'S separating it from its six neighbouring perforations 4 and a channel or duct 6 is formed in each wall 5 at the lower face 3 of the sheet 1; each of the channels 6 being perpendicular to the sides 7 of the adjoining perforations 4 and connecting the mid points. When the sheet 1 is laid onto a flat subsurface 8 closed passages are formed by the channels 6 and the flat subsurface 8 interconnecting each perforation 4 with its neighbours.

In use as a preformed surfacing the sheet l is laid onto a prepared substantially flat surface having a drainage slope, represented by the flat subsurface 8 in FIG. 2, such as asphalt or concrete, to form a pavement. If rain falls onto the upper surface 2 it has only a short distance to flow before it is drained into one of the perforations 4. Water so drained into the perforations 4 can flow in the direction of the fall line of the underlying subsurface 8 through the channels 6 in the lower surface 3 leaving the upper surface 2 free from the possibility of water accomulation. If a heavy precipitation occurs at a rate greater than the channels 6 can accommodate the perforations 4 can each act as a water reservoir allowing water to drain into them and fill then up before the upper surface 2 is affected adversely by an accumulation of water. If the wall 5 thickness of the sheet 1 is kept to a minimum the combined capacity of the perforations 4 could be, depending on the depth of the sheet, equivalent to a considerable water build up on an ordinary pavement surface.

By applying the preformed surfacing to, for instance, an airfield runway, the upper surface 2 of the sheet I can be kept free from accumulation of water even when adverse drainage conditions prevail. Also the relatively small area of surface in contact with a vehicle wheel and the short drainage distance alleviates the problem of aqua planing."

The particular configuration and shape of the perforations 4 described provide a robust structure which is economic in respect of the material quantity required per unit of surface area, but other configurations in which the perforations 4 are of different sizes, or of a different shape, may offer advantages for requirements of specific applications or, for example, the perforations may be stopped just short of the lower surface 3 as shown in FIG. 3 to make it a continuous impervious sheet, provided the perforations were still adequately interconnected by drainage channels.

Such a structure could be formed simply by bonding a flat mating sheet to the flat lower surface 3 of the sheet 1 as previously described ensuring that the channels 6 remain unblocked during the bonding.

Advantages of this construction are that as the subsurface 8 is completely covered by the preformed sheet it is thereby protected from the effects of weather and consequently should have a longer life, also the sheet can be fixed to the subsurface 8 if required by an adhesive with no danger of blocking of the drainage channels 6.

The material from which the sheet 1 is constructed has a certain flexibility so that it can conform to any irregularities in the surface 8 onto which it is to be laid and also requires to be tough to withstand impact loads, for instance, from the wheels of a landing aircraft.

Conveniently the sheet 1 may be formed by moulding a raw material such as a polyurethane or an extended epoxide resin, suitably compounded with reinforcing additives and filler to permit casting and setting it to the required resilience, size and shape. The sheet can be made in one piece or alternatively cut into sections of the shape required to make up the overall dimensions of a particular sub-surface or pavement and to suit local transport and handling facilities.

If the sheet 1 is made from a raw material that can be produced in a variety of colours, markings such as traffic indication signs may be cast in the full depth of the preformed surfacing and will remain there for its life. Alternatively the various traffic routes or usages may be indicated by whole lanes of contrasting colours. Similarly if it is required to provide concealment from the air or to blend with the surrounding environment the surfacing may be formed to any required camouflage colouring or pattern.

The pavement underlying the preformed surfacing will normally be constructed by traditional methods according to the bearing strength requirements and the natural soil conditions and will be laid to falls to provide good surface drainage. The preformed surfacing will then be laid on top of this and fixed in place either by adhesive compatible with the type of material used and with the underlying surface or by spaced anchors, the preferred method offixing being determined by the construction of the underlying pavement. The spaced anchors will be such as to provide a rigid connection between the sheet and the underlying pavement and will be spaced as required by the traffic to use the pavement. Such a spaced anchor could be a metal bolt 9 as shown in the FIGS. 1 and 2 grouted through one of the perforations 4 into the underlying pavement and stopping off below the upper surface 2 of the preformed surfacing. This particular perforation 4 would then be welded to the bolt 9 by filling it with the same compound as that from which the surfacing is manufactured, this providing a rigid connection between the pavement, the bolt 9 and the sheet 1. Light fittings and other surface fittings could be incorporated into the surfacing by similar methods of bolting and welding.

Alternatively, instead of the metal bolt 9 being used, the hole in the subsurface 8 and the corresponding perforation 4 could be filled with a reinforced material such as fibre glass in resin compatible both with the subsurface 8 and the preformed sheet 1 and which forms a good bond with each, thereby forming the required rigid anchor.

The surfacing as described would be highly resistant to both weather and wear by traffic but eventual replacement on account of wear, or repair of occasional damage, could be carried out rapidly, the requisite sections of the sheets 1 cut to the replacement size being if desired, stacked adjacent to the site. lmmediately on close-down of the affected area the faulty section could be cut out and lifted and new sections dropped into place, welded to the surrounding sheet and fixed.

Cleaning of the preformed surfacing in situ could be carried out by vacuum cleaning methods or by hosing down with water.

The preformed pavement surfacing described herein has the advantages that it can be manufactured away from the laying site, it can be laid in large areas in a very short space of time, it can be made in any colour or a variety of colours and, by allowing rain water to drain from the surface within a short distance of the point at which it lands, will not permit a build up of water on its surface.

We claim:

1. A preformed surfacing for a pavement suitable for an aircraft runway surface comprising a sheet of flexible material laid down on a prepared subsurface having a drainage slope, said sheet having a plurality of cavities therein each of which is open to an uppermost surface of the sheet and is surrounded by substantially continuous walls extending from the uppermost to the lowermost surface of the sheet and having ducts extending through said walls providing communication between adjacent cavities, the portions of said substantially continuous walls above the ducts preventing the flow of liquid from the uppermost surface of the sheet into said ducts other than via said cavities, there being ducts from each cavity to at least three adjacent cavities so that in use liquid collecting in the cavities can be drawn away from the sheet through the ducts down the direction of the drainage slope of the prepared subsurface.

v2. A preformed surfacing for a pavement according to claim 1 in which at least some of said cavities are through cavities interconnecting the uppermost surface to a lowermost surface of said sheet.

3. A preformed surfacing for a pavement according to claim 2 in which said interconnecting ducts are channels formed in the lowermost surface of the sheet.

4. A preformed surfacing for a pavement according to claim 1 in which said sheet is provided with a plurality of anchors spaced at discrete intervals whereby it can be fixed to the subsurface.

5. A preformed surfacing for a pavement according to claim 4 in which each anchor is located in one of said drainage cavities in the sheet.

6. A prefonned surfacing for a pavement according to claim 4 in which each of said anchors comprises a membercemented into a recess in said subsurface and bonded into said sheet.

7. A preformed surfacing for a pavement according to claim 4 in which each anchor comprises a plug of castable, bonding material filling arecess in said subsurface and a corresponding adjacent cavity in the sheet.

8. A preformed surfacing for a pavement according to claim 1 in which said cavities extend through only part of said sheet, the lower surface of which presents a continuous impervious face in contact with said subsurface.

9. A preformed surfacing for a pavement according to claim 8 which is fixed to said subsurface by adhesion between said lower surface and the subsurface.

10. A preformed surfacing for a pavement according to claim 1 in which said cavities are of uniform size and regularly spaced from each other.

1 1. A preforming surfacing for a pavement according to claim 10 in which each cavity is surrounded by six cavities, equispaced around said cavity and each equidistant from said cavity, each cavity having six ducts, each of which ducts is connected on one of said surrounding cavities.

12. A preformed surfacing for a pavement according to claim 10 in which each cavity is substantially circular in cross-section in planes parallel to the uppermost surface of the sheet.

13. A preformed surfacing for a pavement according to claim 10 in which each cavity is substantially hexagonal in cross-section in planes parallel to the uppermost surface of the sheet. 

1. A preformed surfacing for a pavement suitable for an aircraft runway surface comprising a sheet of flexible material laid down on a prepared subsurface having a drainage slope, said sheet having a plurality of cavities therein each of which is open to an uppermost surface of the sheet and is surrounded by substantially continuous walls extending from the uppermost to the lowermost surface of the sheet and having ducts extending through said walls providing communication between adjacent cavities, the portions of said substantially continuous walls above the ducts preventing the flow of liquid from the uppermost surface of the sheet into said ducts other than via said cavities, there being ducts from each cavity to at least three adjacent cavities so that in use liquid collecting in the cavities can be drawn away from the sheet through the ducts down the direction of the drainage slope of the prepared subsurface.
 2. A preformed surfacing for a pavement according to claim 1 in which at least some of said cavities are through cavities interconnecting the uppermost surface to a lowermost surface of said sheet.
 3. A preformed surfacing for a pavement according to claim 2 in which said interconnecting ducts are channels formed in the lowermost surface of the sheet.
 4. A preformed surfacing for a pavement according to claim 1 in which said sheet is provided with a plurality of anchors spaced at discrete intervals whereby it can be fixed to the subsurface.
 5. A preformed surfacing for a pavement according to claim 4 in which each anchor is located in one of said drainage cavities in the sheet.
 6. A preformed surfacing for a pavement according to claim 4 in which each of said anchors comprises a membercemented into a recess in said subsurface and bonded into said sheet.
 7. A preformed surfacing for a pavement according to claim 4 in which each anchor comprises a plug of castable, bonding material filling arecess in said subsurface and a corresponding adjacent cavity in the sheet.
 8. A preformed surfacing for a pavement according to claim 1 in which said cavities extend through only part of said sheet, the lower surface of which presents a continuous impervious face in contact with said subsurface.
 9. A preformed surfacing for a pavement according to claim 8 which is fixed to said subsurface by adhesion between said lower surface and the subsurface.
 10. A preformed surfacing for a pavement according to claim 1 in which said cavities are of uniform size and regularly spaced from each other.
 11. A preforming surfacing for a pavement according to claim 10 in which each cavity is surrounded by six cavities, equispaced around said cavity and each equidistant from said cavity, each cavity having six ducts, each of which ducts is connected on one of said surrounding cavities.
 12. A preformed surfacing for a pavement according to claim 10 in which each cavity is substantially circular in cross-section in planes parallel to the uppermost surface of the sheet.
 13. A preformed surfacing for a pavement according to claim 10 in which each cavity is substantially hexagonal in cross-section in planes parallel to the uppermost surface of the sheet. 